The present invention relates to methods of automatic subscription between a mobile station and a base station in a telecommunications network, and to systems implementing them.
The invention belongs to the field of cordless telecommunication network protection.
More precisely, the invention relates to a method and a device making it possible to automatically initiate the subscription procedure which enables a mobile station to obtain rights of access to a cordless base station.
The method and the device of the invention are particularly well adapted to a point to point cordless communication system.
Nevertheless, the invention may also apply to a system containing a limited, defined number of mobile stations per base station.
So as to prevent fraudulent use, cordless communication systems generally utilise security mechanisms in order to be able to authenticate equipment or the equipment user in a cordless system.
For example, the European standard, DECT (xe2x80x9cDigital Enhanced Cordless Telecommunicationsxe2x80x9d, ETSI, EN 300 175), proposes mechanisms to authenticate DECT equipment.
When the authentication phase is successful, a mobile station is authorised to accede to the resources of the base station for which the mobile station has been authenticated.
The authentication procedure is particularly important when the base station allows access to resources of the gateway type to a public network, such as an STN (Switched Telephone Network), or a local network (of the Ethernet type, for example).
The authentication procedure generally requires an authentication key.
This key forms part of the data transferred when the mobile station user proceeds to a subscription or registration procedure with a base station.
Two methods of key allocation are essentially known:
A first method consists in manually keying-in the authentication key by means of a keyboard during the subscription phase. This is the case of the system described in document U.S. Pat. No. 5,572,574.
This method has the drawback of requiring an interface (of the keyboard type) for the user to be able to enter the key.
A second method consists in pre-configuring the system in the factory. Several types of pre-configuration are possible:
all mobile stations and base stations having the same manufacturer share the same key. In this case any mobile station is able to operate with any base station having this same manufacturer. This solution is not very acceptable from the point of view of security;
each mobile station has its own key and is pre-configured to operate with a given base station. This solution has the drawback of not permitting the cordless communication system to be re-configured without the intervention of an operator. This is the case of the system described in document EP-A-0 301 573.
The present invention aims at remedying the above drawbacks.
With this aim in view, the present invention provides a method of subscription of a mobile station to a base station in a telecommunications network, which is remarkable in that a subscription operation is carried out automatically, either
following powering up of the mobile station, if the mobile station is not registered with any base station, or
if, after a predetermined period of time, previously stored in the mobile station, has elapsed, the mobile station has not succeeded in synchronising with and attaching itself to a base station with which the mobile station is already registered.
Thus, the present invention makes it possible to automatically initiate the registration procedure between a mobile station and a base station, by eliminating the key input operation and therefore not requiring any interface for this purpose. In addition, the present invention makes it possible for a mobile station to register itself with a new base station without the intervention of an operator.
Moreover, the present invention has the advantage of being an extremely simple procedure for the user.
It also makes it possible to reduce the cost of the mobile station, given the possibility of doing without the keyboard.
Moreover, it makes it possible to automatically re-configure the association between a mobile station and a base station, which is useful when it is necessary to proceed to the replacement of a defective base station.
Furthermore, by virtue of the present invention, the subscription procedure is activated only when necessary, and not at each start-up, which provides increased security.
According to a particular feature, following power-up of the mobile station:
a test operation is performed, consisting, for the mobile station, of testing whether or not it is already registered with a base station.
This feature has the advantage of avoiding needless initiation of a subscription procedure, in the case where the mobile station is already registered with a base station.
According to a particular feature, during this test operation, it is determined whether or not a subscription table stored in the mobile station contains data.
This feature constitutes a very simple means of knowing if the mobile station is already registered with a base station.
According to a particular feature, following mobile station power-up, if the mobile station is already registered with a base station, an initialisation operation is carried out, consisting in activating a timer by allocating to it a value equal to the above-mentioned predetermined period of time.
This particular feature makes it possible to allocate, in an extremely simple fashion, a predetermined period of time in which to find the base station with which the mobile station is already registered.
According to a particular feature, during the subscription operation, the mobile station carries out a transmission operation, consisting in transmitting an authentication code to the base station.
This feature allows the base station, following verification of the code, to accept or to refuse the mobile station""s request for right of access.
According to a particular feature, a stoppage operation is carried out, consisting of stopping the subscription operation of the mobile station to the base station if the subscription operation has not succeeded before a predetermined period of time has elapsed.
This feature makes it possible for the subscription procedure to be automatically stopped in the event of its failure and enables the system to be secured by limiting the time during which subscription is possible.
The present invention also concerns a mobile station in a telecommunications network, comprising means adapted to implement a method of subscription with a base station such as above.
With the same aim as mentioned above, the present invention proposes, in addition, a method of subscription of a base station to a mobile station in a telecommunications network, which is remarkable in that a subscription operation is carried out automatically, either
following powering up of the base station, if the base station is not registered with any mobile station, or
if, after a predetermined period of time has elapsed, the base station has not succeeded in attaching itself to a mobile station with which this base station is already registered.
The advantages of the method of subscription of a base station to a mobile station and of its particular features are similar to those of the subscription procedure for a mobile station to a base station, mentioned above.
According to a particular feature of the method of subscription of a base station to a mobile station, following power-up of the base station:
a test operation is performed, consisting, for the base station, in testing whether a mobile station is already registered with it.
According to a particular feature, during this test operation, it is determined whether or not a subscription table stored in the base station contains data.
According to a particular feature, following base station power-up, if the base station already has a mobile station registered with it, an initialisation operation is carried out, consisting in activating a timer by allocating to it a value equal to the above-mentioned predetermined period, previously stored in the base station.
According to a particular feature, during the subscription operation, the base station carries out a checking operation, consisting in checking a authentication code transmitted by the mobile station.
According to a particular feature, a stoppage operation is effected, consisting in stopping the operation of subscription of the base station to the mobile station if the subscription operation has not succeeded before a predetermined period of time has elapsed.
The invention also relates to a base station in a telecommunications network comprising means adapted to implementing a method of subscription to a mobile station such as above.
The invention also relates to:
an information storage means, readable by a computer or a microprocessor storing computer program instructions, making it possible to implement a subscription method such as above, and
a partially or totally removable information storage means, readable by a computer or a microprocessor storing computer program instructions, making it possible to implement a subscription method such as above.
The invention also relates to a computer program product comprising instruction sequences to implement a subscription method such as above.
The particular features and advantages, not detailed above, of the mobile station, the base station, the information storage means and the computer program being the same as those for the subscription methods to which they relate, they are not repeated here.